Computer users often focus on the speed of computer microprocessors (e.g., megahertz and gigahertz). Many forget that this speed often comes with a cost—higher electrical power consumption. For one or two home PCs, this extra power may be negligible when compared to the cost of running the many other electrical appliances in a home. However, in data center applications, where thousands of microprocessors may be operated, electrical power requirements can be very important. Not only must a data center operator pay for electricity to operate its many computers, but the operator must also pay to cool the computers. For example, a pair of microprocessors mounted on a single motherboard can draw 200-400 watts or more of power. Multiply that figure by several thousand (or tens of thousands) to account for the many computers in a large data center, and one can readily appreciate the amount of heat that can be generated.
The cost of removing all of the heat can also be a major cost of operating large data centers. That cost typically involves the use of even more energy, in the form of electricity and natural gas, to operate chillers, condensers, pumps, fans, cooling towers, and other related components. Heat removal can also be important because, although microprocessors may not be as sensitive to heat as are people, increases in heat generally can cause increases in microprocessor errors and failures.